The present invention relates to an integrated pressure management system that manages pressure and detects leaks in a fuel system. The present invention also relates to an integrated pressure management system that performs a leak diagnostic for the head space in a fuel tank, a canister that collects volatile fuel vapors from the head space, a purge valve, and all associated hoses.
In a conventional pressure management system for a vehicle, fuel vapor that escapes from a fuel tank is stored in a canister. If there is a leak in the fuel tank, canister or any other component of the vapor handling system, some fuel vapor could exit through the leak to escape into the atmosphere instead of being stored in the canister. Thus, it is desirable to detect leaks.
In such conventional pressure management systems, excess fuel vapor accumulates immediately after engine shut-down, thereby creating a positive pressure in the fuel vapor management system. Thus, it is desirable to vent, or xe2x80x9cblow-off,xe2x80x9d this excess fuel vapor and to facilitate vacuum generation in the fuel vapor management system. Similarly, it is desirable to relieve positive pressure during tank refueling by allowing air to exit the tank at high flow rates. This is commonly referred to as onboard refueling vapor recovery (ORVR).
According to the present invention, a sensor or switch signals that a predetermined pressure exists. In particular, the sensor/switch signals that a predetermined vacuum exists. As it is used herein, xe2x80x9cpressurexe2x80x9d is measured relative to the ambient atmospheric pressure. Thus, positive pressure refers to pressure greater than the ambient atmospheric pressure and negative pressure, or xe2x80x9cvacuum,xe2x80x9d refers to pressure less than the ambient atmospheric pressure.
The present invention is achieved by providing an integrated pressure management apparatus. The integrated pressure management apparatus comprises a housing defining an interior chamber, a pressure operable device separating the chamber into a first portion and a second portion, and a switch signaling displacement of the pressure operable device in response to negative pressure at a first pressure level in the first portion the interior chamber. The housing includes first and second ports communicating with the interior chamber. The first portion of the pressure operable device communicates with the first port, the second portion of the pressure operable device communicates with the second port, and the pressure operable device permits fluid communication between the first and second ports in a first configuration and prevents fluid communication between the first and second ports in a second configuration.
The present invention is also achieved by an integrated pressure management apparatus for a fuel system. The integrated pressure management apparatus comprises a leak detector sensing negative pressure in the fuel system at a first pressure level; and a pressure operable device operatively connected to the leak detector, the pressure operable device relieving negative pressure in the fuel system below the first pressure level and relieving positive pressure above a second pressure level.
The present inventions further achieved by a method of managing pressure in a fuel system. The method comprises providing an integrated assembly including a switch actuated in response to the pressure and a valve actuated to relieve the pressure; and signaling with the switch a negative pressure at a first pressure level.